Currently, restraint arrangements such as airbags are used to increase safety in a vehicle, an accident is recognized using acceleration sensors and a decision is made within a few milliseconds whether and which restraint arrangement are to be triggered. At the same time, differentiation is made between a side impact and a front impact. In both cases, restraint arrangement which partially differ are to be deployed in order to protect the vehicle occupants.
An acceleration sensor of this type is described in German Published Patent Application No. 32 31 800, for example. In this case, a spring-caged inertial mass, which is subjected to the acceleration to be measured, is deflected and the deflection is detected in relation to a spatially fixed reference point. In the event an acceleration threshold is exceeded, a deployment signal is generated. In this case, a massive body includes a first light guide, to whose end a light source is applied. The other end of the light guide, in the idle state and in the deflected state as a function of acceleration, is diametrically opposed to light guides which are connected to photoelements. If an acceleration occurs, the first light guide is moved so that the light from the light source which is guided through the first light guide is received by a different photocell than in the idle state. From this, the acceleration may be established and a restraint arrangement may correspondingly be triggered.
Currently, acceleration sensors are the sole information source for the recognition of a critical situation, on the basis of which the deployment algorithm calculates a deployment decision of the restraint arrangement. With an increasing number of stages in the triggering of the restraint arrangement (e.g., two-stage airbags), the different severities of accidents are differentiated more precisely from one another, in order to trigger the various restraint arrangements and their various stages optimally for the protection of the occupants.
In the event of a side impact, a restraint arrangement is to be triggered in the first milliseconds after the initial contact in order to deploy a protective action for the occupants in a timely manner. However, the typical acceleration sensors only fulfill these requirements unsatisfactorily. The acceleration sensors are also, for example, overtaxed in the event of a frontal impact on the rear side of the vehicle. In the event of a side impact, until now, the conventional systems only differentiated very roughly between an impact in the front or rear. Differentiations such as the penetration of an obstacle into a door or an impact of an object onto the A, B, and/or C pillars of the vehicle are not possible using the current acceleration sensor technology.